15min:

F. MIVEHVAR, J. NOROOZ OLIAEE, N. MOAZZEN-AHMADI, Department of Physics and Astronomy, University of Calgary, Calgary, AB T2N 1N4, Canada.

Infrared spectra of weakly bound Rg--CS₂ (Rg = He, Ne, and Ar) clusters formed in a pulsed supersonic slit-jet expansion have been recorded by exciting the CS_{2 3} fundamental band ( 1535 cm^-1) using a tuneable diode laser. Spectra were well fitted to a conventional semi-rigid asymmetric rotor Hamiltonian. The He--CS₂ spectrum was assigned to an a-type band, while spectra of Ne--CS₂ and Ar--CS₂ were well described by b-type bands, indicating a/b axis switching in transition from the He--CS₂ complex to the Ne--CS₂ and Ar--CS₂ complexes. The results show that the complexes have vibrationally averged T-shaped structures. The determined structural parameters along with the observed vibrational shifts are R=3.81, 3.57 and 3.71 Å, = 80.0, 86.9 and 86.4^\circ and = 0.171, 0.181 and 0.067 cm^-1 for He--CS₂, Ne--CS₂ and Ar--CS₂, respectively. Here, R is the distance between the rare gas and the carbon atom, is the the angle between R and and the CS₂ axis and is the vibrational shift with respect to the free CS₂ monomer.